KA24(e) Throttle Body Modification
Short Explanation
Total cost of this mod: ~$50 for the TB, $2 for the
gasket, and ~$10 in misc. tools if you don't already have them.
What this mod does? The TB on Nissan cars with the
KA24(e) engine (2.4 Liter, 4 Cylinder, DOHC) has a direct bolt-on
replacement TB for the stock Z31 TB. Two manufacturer's produced
TB's for this engine: Nissan and Hitachi. The Hitachi required
some modifications itself...you must replace its linkage (where
the cable hook up) with what you already have on the stock TB.
The Hitachi linkage only allows about 30 degrees of opening and
you need a full 90. You also have to adjust the coolant lines
and use a "T" to join two vacuum lines into one. If
you're lucky enough to find a Nissan TB you should be able to
take of the old and bolt on the new, as the linkage is the same.
You can find the KA24(e) engine on 89-91 240SX, Stanza, and pickups.
The 240SX's I've seen have never had the Nissan TB...only the
Htachi. Stanzas I've seen do have the Nissan, and not the Hitachi.
I never saw a truck to see what they sported...but if its a rear
wheel drive (like the 240SX) I'd assume it also has the Hitachi.
Gains occur because the TB on the KA24(e) engines have
an outlet diameter 10mm larger than on the Z. Both TB's (stock
and KA24(e)) have the same size inlet, but the larger outlet allow
more air to be sucked in on throttle. The AirFlowMeter and computer
compensate for the higher flow of air with more fuel. More air/fuel
mixture = more explosion = more HP. This won't give you gains
like a turbo. The extra "boost" is small, but it is
there. You will get better throttle response and a bit more kick
outta your engine. Good mod and worth it.
Labor time depends on your approach. You HAVE to match
port the intake collector for this mod to do you any good. The
intake collector inlet is ALREADY bigger than the stock Z outlet
by about 5-6mm...so you only need to port it out 4-5 mm more (by
diameter...not on all sides [radius]). I suggest removing the
intake collector to port match. Though it takes a long time, I
wouldn't chance getting metal scraps down into your manifold and
then down the intake valves into the cylinders. Some say stuffing
a towel inside really tight is suffiecient, but I wouldn't chance
it. Pull it off, stuff a towel down there, and then thoroughly
wash it out before sticking it back on. I also took advantage
when I had the intake collector off to paint my driver's side
valve cover to match the rest of my newly painted engine parts.
For the full explanation, Click
Here.